Rich methane premixed laminar flames doped by light unsaturated hydrocarbons

Abstract

In line with the studies presented in the parts I and II of this paper, the structure of a laminar rich premixed methane flame doped with cyclopentene has been investigated. The gases of this flame contains 15.3% (molar) of methane, 26.7% of oxygen and 2.4% cyclopentene corresponding to an equivalence ratio of 1.79 and a ratio C 5 H 8 / CH 4 of 16 %. The flame has been stabilized on a burner at a pressure of 6.7 kPa using argon as dilutant, with a gas velocity at the burner of 36 cm/s at 333 K. The temperature ranged from 627 K close to the burner up to 2027 K. Quantified species included usual methane C 0 -C 2 combustion products, but also propyne, allene, propene, propane, 1-butene, 1,3-butadiene, 1,2-butadiene, vinylacetylene, diacetylene, cyclopentadiene, 1,3-pentadiene, benzene and toluene. A new mechanism for the oxidation of cyclopentene has been proposed. The main reaction pathways of consumption of cyclopentene and of formation of benzene and toluene have been derived from flow rate analyses.

A comparative study of the formation of aromatics in rich methane flames doped by unsaturated compounds

“…3: the unique model reproduces correctly the experimental formation of these two aromatic compounds in the four flames. Compared to our previous simulation with less complete mechanisms [12][13], the simulated maximum mole fractions of benzene have been increased by a factor 1.08, 1.10 and 1.48, for the flame of allene, propyne and 1,3-butadiene, respectively. A detectable concentration of toluene is predicted, but not observed experimentally for the flames containing C 3 additives and the production of toluene is underestimated by a factor 3 for the flame doped with cyclopentene.…”

“…• in the case of 1,3-butadiene, 1,2-butadiene, butynes, vinylacetylene, diacetylene, 1,3-pentadiene, 2-methyl-1,3-butadiene (isoprene), 1-pentene, 3-methyl-1-butene, benzene and toluene [13],…”

“…Reaction base for the oxidation of C 3 -C 4 unsaturated hydrocarbons [12][13] This C 3 -C 4 reaction base [12][13] was built from a review of the literature. The C 3 -C 4 reaction base includes reactions involving C 3 H 2 , C 3 H 3 , C 3 H 4 (allene and propyne), C 3 H 5 , C 3 H 6 , C 4 H 2 , C 4 H 3 , C 4 H 4 , C 4 H 5 , C 4 H 6 (1,3-butadiene, 1,2-butadiene, methyl-cyclopropene, 1-butyne and 2-butyne), C 4 H 7 (6 isomers), as well as some reactions for linear and branched C 5 compounds and the formation of benzene.…”

“…The reactions of cyclopentadiene are part of the mechanism for the oxidation of benzene, but reactions for the consumption of methylcyclopentene and methylcyclopentadiene, obtained by recombination of cyclopentadienyl and methyl radicals had to be added. [12][13][14] In order to investigate the relative importance of the different channels, the formation of aromatic compounds was considered through the C 3 , the C 4 and the C 5 pathways:…”

Experimental study of the structure of a rich premixed 1,3-butadiene/CH4/O2/Ar flame

“…Allene and propyne flames have been previously investigated [6] to study the determinant role of the propargyl radicals in benzene formation. Among the other unsaturated soot precursors implied in the aromatic ring formation, 1,3-butadiene is of primary importance as a primary product in hydrocarbon oxidation and because of its structure involving two conjugated unsaturated bonds.…”